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Table 3 Rotated factor loadings of the factors of the original items of the 15D questionnaires and the AQ20 questionnaire.

From: Comparison between the disease-specific Airways Questionnaire 20 and the generic 15D instruments in COPD

15D questionnaire AQ20 questionnaire
Name of the factor Original item Rotated factor loadings Name of the factor Original item Rotated factor loadings
"Limitation in physical activity" (15.7% of the variation) Usual activities
Breathing
Mobility
Vitality
Sexual activity
0.77
0.75
0.66
0.55
0.47
"Limitation in physical activity" (13.3% of the variation) AQ3
AQ13
AQ11
AQ12
AQ17
0.76
0.70
0.64
0.49
0.48
"Psychic wellbeing" (14.7% of the variation) Depression
Distress
Vitality
0.89
0.79
0.54
"Symptoms at rest" (10.2% of the variation) AQ5
AQ18
AQ9
AQ19
AQ7
0.56
0.48
0.47
0.44
0.42
"Capability of thinking and speaking" (8.1% of the variation) Mental functions
Speech
0.55
0.42
"Emotional concern" (8.9% of the variation) AQ2
AQ16
AQ20
AQ6
AQ17
0.58
0.55
0.54
0.45
0.44
Eating (3.9% of the variation) Eating 0.40 "Limitations in daily activities" (6.0% of the variation) AQ14
AQ10
AQ15
0.57
0.43
0.41
  1. All factors with eigenvalues more >1 and factor loading ≥0.4 were included, maximum likelihood was chosen as the extraction method. The rotational method used was orthogonal, e.g. Varimax.